Study of unflattened photon beams shaped by multileaf collimator using BEAMnrc code

2016 ◽  
Vol 15 (4) ◽  
pp. 392-401
Author(s):  
Ankit kajaria ◽  
Neeraj Sharma ◽  
Shiru Sharma ◽  
Satyajit Pradhan ◽  
Abhijit Mandal ◽  
...  
Keyword(s):  
Beam Line ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Multileaf Collimators ◽  
Depth Dose ◽  
Beamnrc Code ◽  
Flattening Filter Free ◽  
Flattening Filter ◽  
Beam Delivery

AbstractPurposeIn our study basic dosimetric properties of a flattening filter free 6 MV photon beam shaped by multileaf collimators (MLC) is examined using the Monte Carlo (MC) method.Methods and MaterialsBEAMnrc code was used to make a MC simulation model for 6 MV photon beam based on Varian Clinic 600 unique performance linac, operated with and without a flattening filter in beam line. Dosimetric features including central axis depth dose, beam profiles, photon and electron spectra were calculated and compared for flattened and unflattened cases.ResultsDosimetric field size and penumbra were found to be smaller for unflattened beam, and the decrease in field size was less for MLC shaped in comparison with jaw-shaped unflattened beam. Increase in dose rate of >2·4 times was observed for unflattened beam indicating a shorter beam delivery time for treatment. MLC leakage was found to decrease significantly when the flattening filter was removed from the beam line. The total scatter factor showed slower deviation with field sizes for unflattened beam indicating a reduced head scatter.ConclusionsOur study demonstrated that improved accelerator characteristics can be achieved by removing flattening filter from beam line.

scholarly journals Depth Dose Enhancement on Flattening-Filter-Free Photon Beam: A Monte Carlo Study in Nanoparticle-Enhanced Radiotherapy

2020 ◽  
Vol 10 (20) ◽  
pp. 7052
Author(s):  
James C. L. Chow
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Photon Beam ◽  
Depth Range ◽  
Photon Beams ◽  
Dose Enhancement ◽  
Au Nps ◽  
Depth Dose ◽  
Flattening Filter Free ◽  
Flattening Filter

The aim of this study is to investigate the variations of depth dose enhancement (DDE) on different nanoparticle (NP) variables, when using the flattening-filter-free (FFF) photon beam in nanoparticle-enhanced radiotherapy. Monte Carlo simulation under a macroscopic approach was used to determine the DDE ratio (DDER) with variables of NP material (gold (Au) and iron (III) oxide (Fe2O3)), NP concentration (3–40 mg/mL) and photon beam (10 MV flattening-filter (FF) and 10 MV FFF). It is found that Au NPs had a higher DDER than Fe2O3 NPs, when the depths were shallower than 6 and 8 cm for the 10 MV FF and 10 MV FFF photon beams, respectively. However, in a deeper depth range of 10–20 cm, DDER for the Au NPs was lower than Fe2O3 NPs mainly due to the beam attenuation and photon energy distribution. It is concluded that DDER for the Au NPs and Fe2O3 NPs decreased with an increase of depth in the range of 10–20 cm, with rate of decrease depending on the NP material, NP concentration and the use of FF in the photon beam.

scholarly journals Monte Carlo Study of Unflattened Photon Beams Shaped by Multileaf Collimator

2019 ◽  
Vol 9 (2Apr) ◽  
Author(s):  
A Kajaria ◽  
N Sharma ◽  
Sh Sharma ◽  
S Pradhan ◽  
A Mandal ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
Beam Line ◽  
Photon Beam ◽  
Multileaf Collimator ◽  
Photon Beams ◽  
Peripheral Dose ◽  
Depth Dose ◽  
Field Edge ◽  
Flattening Filter

Introduction: This study investigates basic dosimetric properties of unflattened 6 MV photon beam shaped by multileaf collimator and compares them with those of flattened beams.Materials and Methods: Monte Carlo simulation model using BEAM code was developed for a 6MV photon beam based on Varian Clinic 600 unique performance linac operated with and without a flattening filter in beam line. Dosimetric features including lateral profiles, central axis depth dose, photon and electron spectra were calculated for flattened and unflattened cases, separately.Results: An increase in absolute depth dose with a factor of more than 2.4 was observed for unflattened beam which was dependent on depth. PDDs values were found to be lower for unflattened beam for all field sizes. Significant decrease in calculated mlc leakage was observed when the flattening filter was removed from the beam line. The total scatter factor, SCP was found to show less variation with field sizes for unflattened beam indicating a decrease in head scatter. The beam profiles for unflattened case are found to have lower relative dose value in comparison with flattened beam near the field edge, and it falls off faster with distance.Conclusion: Our study showed that increase in the dose rate and lower peripheral dose could be considered as realistic advantages for unflattened 6MV photon beams.

Percentage depth dose fragmentation for investigating and assessing the photon beam dosimetry quality

2018 ◽  
Vol 18 (03) ◽  
pp. 280-284 ◽  
Author(s):  
Mohamed Bencheikh ◽  
Abdelmajid Maghnouj ◽  
Jaouad Tajmouati
Keyword(s):  
Exponential Decay ◽  
Target Volume ◽  
Photon Beam ◽  
Field Size ◽  
Photon Beams ◽  
Energy Agency ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Beam Dosimetry

AbstractAimThe purpose of this study is to introduce a new approach to assess the dosimetry quality of photon beam with energy and irradiation field size. This approach is based on percentage depth dose (PDD) fragmentation for investigating the dosimetry quality.Materials and methodsFor the investigation of the dosimetry quality of 6 and 18 MV photon beams, we have proceeded to fragment the PDD at different field sizes. This approach checks the overall PDD and is not restricted to the exponential decay regions, as per the International Atomic Energy Agency Technical Reports Series No 398 and the American Association of Physicist in Medicine Task Group 51 recommendations.Results and discussionThe 6 MV photon beam deposited more energy in the target volume than the 18 MV photon beam. The dose delivered by the 6 MV beam is greater by a factor of 1·5 than that delivered by the 18 MV beam in the build-up region and the dose delivered by the 6 MV beam is greater by a factor of 2·6 than that delivered by the 18 MV beam in the electronic equilibrium and the exponential decay regions.ConclusionThe dose measured at different points of the beam is higher for 6 MV than for 18 MV photon beam. Therefore, the 6 MV beam is more dosimetrically efficient than the 18 MV beam. Using the proposed approach, we can assess the dosimetry quality by taking into account overall PDD not only in the exponential decay region but also in the field.

scholarly journals Improving Clinical dosimetric Accuracy of cancer treatment using a special quality of Electron and Photon Beam

2021 ◽  
Vol 5 (3) ◽  
Author(s):  
Ayesha Ikhlaq ◽  
Saeed Ahmad Buzdar ◽  
Muhammad Usman Mustafa ◽  
Sana Salahuddin ◽  
Mehr-Un-Nisa ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Electron Beam ◽  
Electron Beams ◽  
Photon Beam ◽  
Field Size ◽  
External Beam Radiation ◽  
Photon Beams ◽  
Depth Dose ◽  
Electron And Photon

In external beam radiation therapy, electron and photon beams have extraordinary characteristics in the treatment of cancer. The electron and photon beam characteristic are essential to study before calibration of machine. This study focused on the dosimetric characteristics of different energies of electron beams for different field size. The basic objective of this work is, to calculate dosimetric parameters and characteristics of electron beam, specially depth dose characteristics along central axis. In this work, 6 MeV, 9 MeV, 12 MeV, 15 MeV and 18 MeV of electron beam and 6 MV and 15 MV of photon beam with different field size is used. Characteristics of depth dose of electron and photon beam in water have analyzed to provide better quality of radiation therapy treatment planning. The different beam characteristics are due to different interactions that occurs between electron beams giving them a definite range whereas photon beams are attenuated leading to dose deposition and much larger range with no definite end. Depth dose characteristics of electron and photon beams do not show same characteristics as interaction of beam with matter depends on the quality of beam. Attenuation and penetration factors change with changing dosimetric parameters. Complete analysis of dosimetric characteristics of electron and photon beam help to choose more accurate beam for the treatment of cancer. This work will help to increase accuracy in treatment of cancer with radiotherapy.

scholarly journals Use of Flattening Filter-Free Photon Beams in Treating Medulloblastoma: A Dosimetric Evaluation

ISRN Oncology ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Pichandi Anchineyan ◽  
Ganesh K. Mani ◽  
Jerrin Amalraj ◽  
Balaji Karthik ◽  
Surega Anbumani
Keyword(s):  
Intensity Modulated Radiation Therapy ◽  
Data Sets ◽  
Photon Beams ◽  
Treatment Efficiency ◽  
Multileaf Collimators ◽  
Conformal Therapy ◽  
Flattening Filter Free ◽  
Flattening Filter ◽  
Ct Data ◽  
Craniospinal Axis

Aim. To evaluate the dosimetric benefits of flattening filter-free (FFF) photon beams in intensity modulated radiation therapy (IMRT) and Rapid Arc (RA) over conventional CSI methods. Methods and Materials. Five patients treated with IMRT using static multileaf collimators (MLC) were randomly selected for this retrospective study. Dynamic MLC IMRT, RA, and conformal therapy (3DCRT) were iterated with the same CT data sets with and without flattening filter photons. Total dose prescribed was 28.80 Gy in 16 fractions. Dosimetric parameters such as Dmax⁡, Dmin⁡, Dmean, V95%, V107%, DHI, and CI for PTV and Dmax⁡, Dmean, V80%, V50%, V30%, and V10% for OARs were extracted from DVHs. Beam on time (BOT) for various plans was also compared. Results. FFF RA therapy (6F_RA) resulted in highly homogeneous and conformal doses throughout the craniospinal axis. 3DCRT resulted in the highest V107% (SD) 46.97±28.6, whereas flattening filter (FF) and FFF dynamic IMRT had a minimum V107%. 6F_RA and 6F_DMLC resulted in lesser doses to thyroid, eyes, esophagus, liver, lungs, and kidneys. Conclusion. FFF IMRT and FFF RA for CSI have definite dosimetric advantages over 3DCRT technique in terms of target coverage and OAR sparing. Use of FFF in IMRT resulted in 50% reduction in BOT, thereby increasing the treatment efficiency.

Calypso’s array attenuation

2015 ◽  
Vol 14 (2) ◽  
pp. 202-207
Author(s):  
Célia Silva ◽  
Dalila Mateus ◽  
Sandra Vieira ◽  
Milton Rodrigues ◽  
Margarida Eiras ◽  
...  
Keyword(s):  
Treatment Plan ◽  
Field Size ◽  
Beam Angle ◽  
Photon Beams ◽  
Beam Path ◽  
Attenuation Effect ◽  
Ion Chamber ◽  
Flattening Filter Free ◽  
Flattening Filter ◽  
Attenuation Values

AbstractIntroductionThe Calypso 4D Localization System gives the possibility to track the tumour during treatment, with no additional ionising radiation delivered. To monitor the patient continuously an array is positioned above the patient during the treatment. We intend to study, for various gantry angles, the attenuation effect of the array for 6- and 10 MV and flattening filter free (FFF) 6- and FFF 10 MV photon beams.Materials and methodsMeasurements were performed using an ion chamber placed in a slab phantom positioned at the linac isocenter for 6 MV, 10 MV, FFF 6 MV and FFF 10 MV photon beams. Measurements were performed with and without array above the phantom for 0°, 10°, 20°, 40° and 50° beam angle for a True Beam STx linac, for 5×5 and 10×10 and 15×15 cm2 field size beams to evaluate the attenuation of the array. A VMAT treatment plan was measured using an ArcCheck with and without the array in the beam path.Results and discussionAttenuation measured values were up to 3%. Attenuation values were between 1 and 2% with the exception of the 30°–50° gantry angles which were up to 3.3%. The ratio values calculated in the ArcCheck for relative dose and absolute dose 10 were both 1·00.ConclusionAttenuation of the treatment beam by the Calypso array is within acceptable limits.

Evaluation of dosimetric parameters of small fields of 6 MV flattening filter free photon beam measured using various detectors against Monte Carlo simulation

2020 ◽  
pp. 1-8
Author(s):  
Gopinath Mamballikalam ◽  
S Senthilkumar ◽  
P. M. Jayadevan ◽  
R. C. Jaon bos ◽  
P. M. Ahamed Basith ◽  
...  
Keyword(s):  
Volume Averaging ◽  
Field Size ◽  
Detector Response ◽  
Surface Dose ◽  
Output Factor ◽  
Depth Dose ◽  
Flattening Filter Free ◽  
Small Fields ◽  
Flattening Filter ◽  
Mc Simulation

Abstract Purpose: This study aims to evaluate dosimetric parameters like percentage depth dose, dosimetric field size, depth of maximum dose surface dose, penumbra and output factors measured using IBA CC01 pinpoint chamber, IBA stereotactic field diode (SFD), PTW microDiamond against Monte Carlo (MC) simulation for 6 MV flattening filter-free small fields. Materials and Methods: The linear accelerator used in the study was a Varian TrueBeam® STx. All field sizes were defined by jaws. The required shift to effective point of measurement was given for CC01, SFD and microdiamond for depth dose measurements. The output factor of a given field size was taken as the ratio of meter readings normalised to 10 × 10 cm2 reference field size without applying any correction to account for changes in detector response. MC simulation was performed using PRIMO (PENELOPE-based program). The phase space files for MC simulation were adopted from the MyVarian Website. Results and Discussion: Variations were seen between the detectors and MC, especially for fields smaller than 2 × 2 cm2 where the lateral charge particle equilibrium was not satisfied. Diamond detector was seen as most suitable for all measurements above 1 × 1 cm2. SFD was seen very close to MC results except for under-response in output factor measurements. CC01 was observed to be suitable for field sizes above 2 × 2 cm2. Volume averaging effect for penumbra measurements in CC01 was observed. No detector was found suitable for surface dose measurement as surface ionisation was different from surface dose due to the effect of perturbation of fluence. Some discrepancies in measurements and MC values were observed which may suggest effects of source occlusion, shift in focal point or mismatch between real accelerator geometry and simulation geometry. Conclusion: For output factor measurement, TRS483 suggested correction factor needs to be applied to account for the difference in detector response. CC01 can be used for field sizes above 2 × 2 cm2 and microdiamond detector is suitable for above 1 × 1 cm2. Below these field sizes, perturbation corrections and volume averaging corrections need to be applied.

scholarly journals Contrast Enhancement for Portal Imaging in Nanoparticle-Enhanced Radiotherapy: A Monte Carlo Phantom Evaluation Using Flattening-Filter-Free Photon Beams

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 920 ◽  
Author(s):  
Aniza Abdulle ◽  
James C. L. Chow
Keyword(s):  
Monte Carlo ◽  
Contrast Enhancement ◽  
Beam Energy ◽  
Photon Beam ◽  
Nanoparticle Concentration ◽  
Photon Beams ◽  
Portal Imaging ◽  
Flattening Filter Free ◽  
Rate Of Increase ◽  
Flattening Filter

Our team evaluated contrast enhancement for portal imaging using Monte Carlo simulation in nanoparticle-enhanced radiotherapy. Dependencies of percentage contrast enhancement on flattening-filter (FF) and flattening-filter-free (FFF) photon beams were determined by varying the nanoparticle material (gold, platinum, iodine, silver, iron oxide), nanoparticle concentration (3–40 mg/mL) and photon beam energy (6 and 10 MV). Phase-space files and energy spectra of the 6 MV FF, 6 MV FFF, 10 MV FF and 10 MV FFF photon beams were generated based on a Varian TrueBeam linear accelerator. We found that gold and platinum nanoparticles (NP) produced the highest contrast enhancement for portal imaging, compared to other NP with lower atomic numbers. The maximum percentage contrast enhancements for the gold and platinum NP were 18.9% and 18.5% with a concentration equal to 40 mg/mL. The contrast enhancement was also found to increase with the nanoparticle concentration. The maximum rate of increase of contrast enhancement for the gold NP was equal to 0.29%/mg/mL. Using the 6 MV photon beams, the maximum contrast enhancements for the gold NP were 79% (FF) and 78% (FFF) higher than those using the 10 MV beams. For the FFF beams, the maximum contrast enhancements for the gold NP were 53.6% (6 MV) and 53.8% (10 MV) higher than those using the FF beams. It is concluded that contrast enhancement for portal imaging can be increased when a higher atomic number of NP, higher nanoparticle concentration, lower photon beam energy and no flattening filter of photon beam are used in nanoparticle-enhanced radiotherapy.

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